The present invention generally relates to a three-dimensional virtual reality space display processing apparatus, a three-dimensional virtual reality space display processing method, and an information providing medium and, more particularly, to a three-dimensional virtual reality space display processing apparatus, a three-dimensional virtual reality space display processing method, and an information providing medium that allow setting of a direction of the sight line of an avatar regardless of moving direction thereof.
A cyberspace service named Habitat.TM. is known in the so-called personal computer communications services such as NIFTY-Serve.TM. of Japan and CompuServe.TM. of U.S. in which a plurality of users connect their personal computers via modems and public telephone network to the host computers installed at the centers of the services to access them in predetermined protocols. Development of Habitat started in 1985 by Lucas Film of the U.S., operated by Quantum Link, one of U.S. commercial networks, for about three years. Then, Habitat started its service in NIFTY-Serve as Fujitsu Habitat.TM. in February 1990. In Habitat, users can send their alter egos called avatars (the incarnation of a god figuring in the Hindu mythology) into a virtual city called Populopolis drawn by two-dimensional graphics to have a chat (namely, a realtime conversation based on text entered and displayed) with each other. For further details of Habitat, refer to the Japanese translation of "Cyberspace: First Steps," Michael Benedikt, ed., 1991, MIT Press Cambridge, Mass., ISBN0-262-02327-X, the translation being published Mar. 20, 1994, by NTT Publishing, ISBN4-87188-265-9C0010, pp. 282-307.
In such a virtual reality space, a user can move his or her avatar in any direction to enjoy a variety of virtual experiences.
The avatar's moving direction can be specified in one of forward, backward, left, and right for example. In some systems, the sight line of an avatar can be changed upward or downward for example.
If a sight line direction 302 of an avatar 301 is directed upward for example as shown in FIG. 33, the user can surely see an image in the upper direction in a virtual reality space 300. However, if the avatar 301 is moved forward with its sight line fixed in that direction (normally, when an avatar is moved forward relative to its viewpoint, it moves into the depth of the screen; for convenience of description, the left side of the screen is assumed to be avatar's forward moving direction), the avatar 301 moves in the sight line direction 302, raising itself gradually from a ground level (horizontal plane) 304 in a tilt manner because the avatar 301 is designed to move in the sight line direction 302. Consequently, the display of the virtual reality space viewed from the viewpoint of the avatar 301 becomes an unnatural display not actually seen in a real space in which people move around with their feet supported by the ground.